FIELD OF THE INVENTION
The invention relates to a printing press having an actuator and a chamber partly surrounding the actuator.
A printing press includes various kinds of actuators, which are used in the atmosphere prevailing in the printing press. As a rule, this atmosphere is laden with volatile components of printing inks and coatings and, particularly in the region of a delivery of a sheet-fed printing press, it is additionally laden with a powder used for dusting freshly printed sheets.
This actuator, for example, includes a conveyor chain of a chain conveyor, an axially oscillating tappet of a jogger, or a gear wheel of an adjusting drive mechanism for a sheet brake, or the like, the gear wheel meshing with a rack.
An actuator that includes a conveyor chain of a chain conveyor and a chamber partly surrounding the actuator have become known heretofore, for example, from the published German Patent Document DE 43 25 251 A1. The chamber disclosed therein is formed of two opposed guide rails and a mounting support carrying the latter which, together with the guide rails, forms a profile rail of C-shaped cross section, so that the chamber forms an elongated interior with an open long side. The actuator partly surrounded by this chamber serves to draw a web of printing material into a dryer downstream of a web-fed rotary printing press; the conveyor chain is embodied, in particular, as a roller chain, to which an infeed element engaging the web of printing material is secured. In an exemplary embodiment, the open long side is covered by elastic leaves or plates in a manner that the leaves avoid or evade the infeed element along the path thereof past the open long side and, on a side of the infeed element that is upline, as viewed in the infeed direction, cover a portion of the long side again that is temporarily uncovered because of the avoidance or evasion. The interior of the chamber is thus exposed to the atmosphere prevailing in the dryer only via a gap that migrates during the infeeding of the web and is thus largely protected against penetration by volatile components contained in printing inks, which would otherwise condense again in the interior and thereby contaminate or soil the roller chain and the guide rails.
Using a chain conveyor of this type, that is protected against contamination, for transporting sheets in a sheet-fed printing press would not, however, achieve the protective effect attainable when the heretofore known device is used as intended. Instead, it would simultaneously produce a plurality of gaps corresponding to the gap described hereinabove, wherever a gripper system, transporting the sheets as the gripper system revolves during operation, is located, and these gaps would revolve along the chain conveyor at the processing speed.
Thus, the interior would be in communication constantly, although at varying locations, with the ambient atmosphere along the temporarily covered open long side of the interior chamber. Effective protection against the penetration by floating substances into the interior would consequently not be achieved, even though, in sheet-fed printing presses, powder particles occur as additional floating substances which, depending upon the composition thereof, do not only have a contaminating or soiling, but also an abrasive effect. Furthermore, the leaves would be subject to considerable wear, on the one hand, because of friction between the gripper systems and the leaves that are prestressed in the closing direction by their evasive motion and, on the other hand, because of the deformations of the leaves that occur during the sheet processing cycle.
An actuator that includes a tappet, which oscillates axially during operation, and forms part of a jogger for aligning sheets transferred to a pile has become known heretofore, for example, from the German Utility Model (DE-GM) 75 13 266. This tappet is composed of a rod that carries a tappet plate and, to adjust to the size of sheets to be aligned, is received adjustably in the longitudinal direction of the rod and fixably in a sleeve; an adjusting screw inserted into the sleeve and engaging a longitudinal groove of the rod serves for fixing it. The sleeve is, in turn, received longitudinally displaceably in a locally stationary bearing bushing; it is secured against being rotated about the longitudinal axis thereof and, on an end of the sleeve that protrudes past the bearing bushing on a side towards an impact plate, it has a cam follower in the form of a ball bearing, that is positioned against or in engagement with an axial cam by which the tappet is periodically oscillatingly adjustable in the longitudinal direction thereof. The adjusting force of the axial cam counteracts a restoring force on the part of a spring. This spring is supported, at one end thereof, on an end face of the bearing bushing distal from the impact plate and, on the other end thereof, in a cap which is thrust onto a portion of the sleeve protruding past this face end and is axially secured against the action of the spring. To secure the sleeve and thus the impact plate against rotation or torsion about the longitudinal axis of the assembled tappet, the sleeve has a further ball bearing, which is braced on a guiding surface. To assure suitable protection of the aforementioned longitudinal groove from a deposition of powder therein, this longitudinal groove is mounted on the underside of the rod. The aforementioned ball bearings, conversely, when the jogger is used as intended, are exposed fully and completely to a powder-laden atmosphere and therefore require careful maintenance.
An actuator that includes a gear wheel meshing with a rack and forming part of an adjusting drive mechanism for a sheet brake, and a chamber partly surrounding the actuator, have become known heretofore from the published German Patent Document DE 197 09 083 C1.
The sheet brake includes a plurality of braking devices and a guide crossbar for carrying them; along the crossbar, the braking devices can each be shifted by a respective adjusting drive mechanism assigned to a given braking device. The respective adjusting drive mechanism in this case is a motor, that is connected to the respective braking device, and that has a transmission block with a power takeoff shaft provided with a gear wheel that meshes with a rack disposed parallel to the guide crossbar. The rack and the guide crossbar, as well as the motor with the transmission block and a respective carriage that supports the applicable braking element in the form of a suction wheel and is movable relative to the guide crossbar, are enclosed by a housing having an opening that extends along the guide crossbar and having a respective support arm, that carries the respective suction wheel and is connected to one of the carriages, protruding therefrom, so that a chamber partly surrounding an actuator is formed. This chamber serves the purpose of reducing the risk of contamination of the device parts located inside the chamber. To improve the sought-after result, the opening of the chamber is provided with a flexible seal in the form of felt or foam, or in the form of a brush.